A conventional optical device such as an optical waveguide device is generally manufactured by laminating an optical waveguide layer onto a substrate to arrange many optical device elements, such as optical waveguide device elements, in a wafer and cutting the wafer into the individual optical device elements by means of, for example, dicing (for example, please refer to Patent Publication 1 indicated below). A disc blade is typically used to cut the wafer.
FIG. 9 is a perspective view showing an example of such an optical device. An optical device 200 has a substrate 202 and an optical waveguide layer 204 laminated thereon. The waveguide layer 204 has first lateral surfaces 206a, 206b each of which an optical fiber F1 or an optical fiber array is connected to and second lateral surfaces 208 each of which such an optical fiber F1 or an optical fiber array is not connected to. The substrate 202 has also lateral surfaces 216 on the same sides as those of the second lateral surfaces 208 of the waveguide layer 204, and the second lateral surface 208 and the lateral surface 216 of the substrate 202 on the same side are located in a single plane. The waveguide layer 204 is made of polymer.
Further, an optical filter F2 is provided in the middle of the waveguide layer 204 in a light-propagating direction 210a. The filter F2 is inserted into an optical-filter-mounting groove 212 made in the waveguide layer 204 and the substrate 202 and fixed therein by means of a filter adhesive A2 filled into a gap 211 between the filter F2 and the filter-mounting groove 212. Further, a fiber adhesive A1 is filled into a gap 213 between the fiber F1 and the waveguide layer 204 and into an optical-fiber-coupling groove 214b across the substrate 202 in a transverse direction 210b at an end of the fiber F1. The filter adhesive A2 is a resin selected so that a refractive index thereof is close to that of a core 204a of the waveguide layer 204, while the fiber adhesive A1 is a resin selected so that a refractive index thereof is close to that of a core of the fiber F1.
Patent Publication 1: Japanese Patent Laid-open Publication No. 2001-281479
When the optical device 200 in the form shown in FIG. 9 is cut away from a wafer by means of a dicing blade, there is a problem that cutting dust formed of a material of the waveguide layer 204 are attached to the dicing blade so that the dicing blade tends to be clogged with the dust. This problem especially tends to happen when the waveguide layer 204 is made of polymer.
Further, when an uncured fiber adhesive A1 is dropped into the fiber-coupling groove 214b, the fiber adhesive A1 may flow into the filter-mounting groove 212. Specifically, a width of the fiber-coupling groove 214b is within a range of 50-300 μm, the lateral surface 216 of the substrate 202 is formed with a fine indented pattern by means of the dicing blade, and the gap 211 between the filter-mounting groove 212 and the filter F2 is within a range of 15-600 μm. In this connection, each of the groove 214b, the fine indented pattern and the gap 211 has a function of allowing the uncured resin (adhesive) to travel far away therealong. After the fiber adhesive A1 is dropped into the fiber-coupling groove 214b, the fiber adhesive A1 expands in the fiber-coupling groove 214b in the transverse direction 210b, travels along the fine indented pattern on the lateral surfaces 208, 216, reaches the filter-mounting groove 212 and enters it. In this case, since the refractive index of the fiber adhesive A1 is different from that of the filter adhesive A2, a reflective return light of the optical device 200 is possibly increased. Similarly, after the filter adhesive A2 is dropped into the filter-mounting groove 212, the filter adhesive A2 may enter the fiber-coupling groove 214b. 
It is therefore the first object of the present invention to provide an optical device which can prevent a dicing blade form being clogged when a wafer is cut by means thereof
Further, it is the second object of the present invention to provide an optical device which can prevent unnecessary expansion of a resin used in the optical device.